U.S. patent number 8,624,102 [Application Number 13/586,794] was granted by the patent office on 2014-01-07 for metal trace fabrication for optical element.
This patent grant is currently assigned to Palo Alto Research Center Incorporated. The grantee listed for this patent is Harold Ackler, Hing Wah Chan, David G. Duff, John S. Fitch, David K. Fork, Scott E. Solberg, Michael C. Weisberg. Invention is credited to Harold Ackler, Hing Wah Chan, David G. Duff, John S. Fitch, David K. Fork, Scott E. Solberg, Michael C. Weisberg.
United States Patent |
8,624,102 |
Chan , et al. |
January 7, 2014 |
Metal trace fabrication for optical element
Abstract
A system may include an optical element including a surface
defining a recess, conductive material disposed within the recess,
and a solder mask disposed over a portion of the conductive
material. The solder mask may define an aperture through which
light from the optical element may pass. Some aspects provide
creation of an optical element including a surface defining a
recess, deposition of conductive material on the surface such that
a portion of the deposited conductive material is disposed within
the recess, and substantial planarization of the surface to expose
the portion of the conductive material disposed within the
recess.
Inventors: |
Chan; Hing Wah (San Jose,
CA), Ackler; Harold (Boise, ID), Solberg; Scott E.
(Mountain View, CA), Fitch; John S. (Los Altos, CA),
Fork; David K. (Mountain View, CA), Duff; David G.
(Portola Valley, CA), Weisberg; Michael C. (Woodside,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Chan; Hing Wah
Ackler; Harold
Solberg; Scott E.
Fitch; John S.
Fork; David K.
Duff; David G.
Weisberg; Michael C. |
San Jose
Boise
Mountain View
Los Altos
Mountain View
Portola Valley
Woodside |
CA
ID
CA
CA
CA
CA
CA |
US
US
US
US
US
US
US |
|
|
Assignee: |
Palo Alto Research Center
Incorporated (Palo Alto, CA)
|
Family
ID: |
39675132 |
Appl.
No.: |
13/586,794 |
Filed: |
August 15, 2012 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20120305405 A1 |
Dec 6, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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12909488 |
Oct 21, 2010 |
8389851 |
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11782609 |
Jul 24, 2007 |
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60899150 |
Feb 2, 2007 |
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Current U.S.
Class: |
136/246 |
Current CPC
Class: |
H01L
31/054 (20141201); H01L 31/0547 (20141201); H01L
2224/0554 (20130101); Y02E 10/52 (20130101); H01L
24/13 (20130101); H01L 24/16 (20130101); H01L
2224/16237 (20130101); H01L 2224/13101 (20130101); Y10T
156/10 (20150115); H01L 2924/00014 (20130101); H01L
2224/05573 (20130101); H01L 2224/05568 (20130101); H01L
2224/13101 (20130101); H01L 2924/014 (20130101); H01L
2924/00014 (20130101); H01L 2924/00014 (20130101); H01L
2224/05599 (20130101); H01L 2924/00014 (20130101); H01L
2224/0555 (20130101); H01L 2924/00014 (20130101); H01L
2224/0556 (20130101) |
Current International
Class: |
H01L
31/05 (20060101); H01L 31/052 (20060101) |
Field of
Search: |
;136/246 |
References Cited
[Referenced By]
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Other References
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Design Overview", 2000 IEEE, pp. 1495-1497. cited by applicant
.
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Conference Record of the 28th IEEE Photovoltaic Specialists
Conference (2000) pp. 1416-1419. cited by applicant .
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by applicant .
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PV", Presented at the 19th European Photovoltaic Solar Energy
Conf., Jun. 7-11, 2004, Paris, 4 pages. cited by applicant .
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System for Tandem Solar Cells", WCPEC2006, 4 pages, 2006. cited by
applicant .
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applicant.
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Primary Examiner: Berdichevsky; Miriam
Attorney, Agent or Firm: Bever, Hoffman & Harms, LLP
Bever; Patrick T.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a divisional of U.S. patent application
Ser. No. 12/909,488, filed on Oct. 21, 2010 and entitled "Metal
Trace Fabrication For Optical Element" which is a divisional of
U.S. patent application Ser. No. 11/782,609, filed on Jul. 24, 2007
and entitled "Metal Trace Fabrication For Optical Element" which
claims priority to U.S. Provisional Patent Application Ser. No.
60/899,150, filed on Feb. 2, 2007 and entitled "Concentrated
Photovoltaic Energy Designs", the contents of which are
incorporated herein by reference for all purposes.
Claims
The invention claimed is:
1. A method comprising: depositing a first conductive material on a
solid optical element consisting essentially of glass having a flat
first surface including a concave surface portion, a convex second
surface disposed opposite to the flat first surface, and a
cylindrical pedestal structure disposed on the concave surface
portion, the cylindrical pedestal structure including a flat second
surface that faces away from the flat first surface and defines at
least one elongated radial recess, wherein depositing the first
conductive material comprises depositing the first conductive
material on the flat second surface of the cylindrical pedestal
structure such that at least a portion of the first conductive
material is disposed in the at least one elongated radial recess;
depositing photoresist on the first conductive material; removing a
portion of the photoresist to expose the portion of the first
conductive material disposed in the at least one elongated radial
recess; plating the exposed portion of the first conductive
material with a second conductive material; removing a remaining
portion of the photoresist; and removing unplated portions of the
first conductive material.
2. A method according to claim 1, wherein: the first conductive
material and the second conductive material are substantially
similar, and removing the unplated portions comprises etching the
unplated portions of the first conductive material and a portion of
the second conductive material.
3. A method according to claim 1, wherein: the first conductive
material and the second conductive material are different; and
removing the unplated portions comprises selectively etching the
unplated portions of the first conductive material without etching
the second conductive material.
4. A method according to claim 1, further comprising: depositing a
solder mask over a portion of second conductive material such that
the solder mask defines an aperture through which light from the
optical element may pass and such that an end portion of the second
conductive material is exposed inside the aperture.
5. A method according to claim 4, further comprising: disposing a
solar cell over the aperture; and coupling a terminal of a solar
cell to the exposed end portion of the second conductive
material.
6. A method according to claim 1, wherein depositing the first
conductive material comprises depositing the first conductive
material on the flat second surface of the cylindrical pedestal
structure such that portions of the conductive material are
disposed in four elongated radial recesses defined in the flat
second surface, and wherein said plating comprises forming said
second conductive material over the first conductive material
disposed in the four elongated radial recesses.
7. A method according to claim 6, wherein: the first conductive
material and the second conductive material are substantially
similar, and removing the unplated portions comprises etching the
unplated portions of the first conductive material and a portion of
the second conductive material disposed outside of said four
elongated radial recesses.
8. A method according to claim 6, wherein: the first conductive
material and the second conductive material are different; and
removing the unplated portions comprises selectively etching the
unplated portions of the first conductive material disposed outside
of said four elongated radial recesses without etching the second
conductive material disposed inside said four elongated radial
recesses.
9. A method according to claim 6, further comprising: depositing a
solder mask over a portion of second conductive material disposed
inside each of the four elongated radial recesses such that the
solder mask defines an aperture through which light from the
optical element may pass, and such that respective end portions of
said second conductive material disposed inside each of the four
elongated radial recesses is exposed inside the aperture.
10. A method according to claim 9, further comprising: disposing a
solar cell over the aperture; and coupling a terminal of a solar
cell to the exposed end portions of said second conductive material
disposed inside each of the four elongated radial recesses is
exposed inside the aperture.
Description
BACKGROUND
1. Field
Some embodiments generally relate to electrical systems
incorporating one or more optical elements. More specifically,
embodiments may relate to an optical element efficiently adapted
for interconnection to electrical devices.
2. Brief Description
In some conventional devices, an optical element (e.g., a lens) may
include metal traces for interconnection to an electrical circuit.
The metal traces may be fabricated on and/or within the optical
element using any of several known techniques. For example, the
metal traces may be deposited using thin or thick film lithography.
Lithography, however, requires expensive equipment and
time-consuming processes.
Since a typical optical element does not include distinguishing
surface features, lithographic techniques also require fiducial
marks for proper alignment of the metal traces on the optical
element. However, the placement of the fiducial marks on the
optical element is also difficult due to the lack of surface
features and the material of which the optical element is composed
(e.g., glass).
What is needed is a system to efficiently incorporate metal traces
into an optical element.
SUMMARY
To address at least the foregoing, some aspects provide a method,
means and/or process steps to create an optical element including a
surface defining a recess, deposit conductive material on the
surface such that a portion of the deposited conductive material is
disposed within the recess, and substantially planarize the surface
to expose the portion of the conductive material disposed within
the recess.
Creation of the optical element may include molding the optical
element with a mold defining the optical element and the recess.
Also or alternatively, deposition of the conductive material may
include placing a stencil on the optical element prior to metal
spraying the conductive material onto the optical element.
In some aspects, a reflective material is deposited on the optical
element and not on the surface, an electrical isolator is deposited
on the reflective material but not on the surface, and the
conductive material is deposited on the electrical isolator.
Aspects may include deposition of a solder mask over the exposed
portion of the conductive material, wherein the solder mask defines
an aperture through which light from the optical element may pass.
Further to the foregoing aspects, a terminal of a solar cell may be
coupled to the exposed portion of the conductive material such that
a portion of the solar cell is disposed over the aperture.
In other aspects, provided are an optical element including a
surface defining a recess, conductive material disposed within the
recess, and a solder mask disposed over a portion of the conductive
material. The solder mask may define an aperture through which
light from the optical element may pass. The optical element may
comprise a transparent portion including the surface, and light may
pass from the transparent portion through the aperture.
According to further aspects, a reflective material may be disposed
on the optical element and not on the surface, an electrical
isolator may be disposed on the reflective material and not on the
surface, and second conductive material may be disposed on the
electrical isolator. Some aspects include a solar cell having a
terminal coupled to a portion of the conductive material exposed by
the aperture, wherein a portion of the solar cell is disposed to
receive the light from the aperture.
The claims are not limited to the disclosed embodiments, however,
as those in the art can readily adapt the description herein to
create other embodiments and applications.
BRIEF DESCRIPTION OF THE DRAWINGS
The construction and usage of embodiments will become readily
apparent from consideration of the following specification as
illustrated in the accompanying drawings, in which like reference
numerals designate like parts.
FIG. 1 is a flow diagram of a method according to some
embodiments.
FIG. 2 is a perspective view of a portion of an optical element
according to some embodiments.
FIG. 3 is a cross-sectional view of a portion of an optical element
according to some embodiments.
FIG. 4 is a perspective view of a portion of an optical element
with conductive material disposed thereon according to some
embodiments.
FIG. 5 is a cross-sectional view of a portion of an optical element
with conductive material disposed thereon according to some
embodiments.
FIG. 6 is a perspective view of a substantially planarized portion
of an optical element according to some embodiments.
FIG. 7 is a cross-sectional view of a substantially planarized
portion of an optical element according to some embodiments.
FIG. 8 is a flow diagram of a method according to some
embodiments.
FIG. 9A is a perspective view of a transparent optical element
according to some embodiments.
FIG. 9B is a cross-sectional view of a transparent optical element
according to some embodiments.
FIG. 10A is a perspective view of a transparent optical element
with reflective material disposed thereon according to some
embodiments.
FIG. 10B is a cross-sectional view of a transparent optical element
with reflective material disposed thereon according to some
embodiments.
FIG. 11A is a perspective view of an optical element with an
electrical isolator disposed thereon according to some
embodiments.
FIG. 11B is a cross-sectional view of an optical element with an
electrical isolator disposed thereon according to some
embodiments.
FIG. 12A is a perspective view of an optical element with
conductive material disposed thereon according to some
embodiments.
FIG. 12B is a cross-sectional view of an optical element with
conductive material disposed thereon according to some
embodiments.
FIG. 13A is a perspective view of an optical element after
planarization of a portion thereof according to some
embodiments.
FIG. 13B is a cross-sectional view of an optical element after
planarization of a portion thereof according to some
embodiments.
FIG. 14A is a perspective view of a solder mask deposited on an
optical element according to some embodiments.
FIG. 14B is a cross-sectional view of a solder mask deposited on an
optical element according to some embodiments.
FIG. 15 is a close-up cross-sectional view of an optical element
including a solar cell according to some embodiments.
DETAILED DESCRIPTION
The following description is provided to enable any person in the
art to make and use the described embodiments and sets forth the
best mode contemplated for carrying out some embodiments. Various
modifications, however, will remain readily apparent to those in
the art.
FIG. 1 is a flow diagram of process 10 according to some
embodiments. Process 10 may be performed by any combination of
machine, hardware, software and manual means.
Initially, an optical element is created at S12. The optical
element includes a surface defining a recess, and may be composed
of any suitable material or combination of materials. According to
some embodiments, the optical element may be configured to
manipulate and/or pass desired wavelengths of light. The optical
element may comprise any number of disparate materials and/or
elements (e.g., lenses, mirrors, etc.) according to some
embodiments.
The optical element may be created using any combination of devices
and systems that is or becomes known. Some embodiments of S12
include depositing a liquid or powder into a mold and cooling,
heating and/or pressuring the mold. The mold may define the optical
element as well as the aforementioned recesses. Alternatively, the
recesses may be formed (e.g., by etching, milling, etc.) after the
optical element is molded.
FIG. 2 is a perspective view of a portion of optical element 100
according to some embodiments, and FIG. 3 is a cross-sectional view
of optical element 100. FIGS. 2 and 3 show only a portion of
optical element 100 in order to illustrate that optical element 100
may exhibit any suitable shape or size. Element 100 may be
fabricated according to S12 of FIG. 1, but S12 is not limited
thereto.
The illustrated portion of optical element 100 comprises surface
110, recess 120 and recess 130. In the present description, surface
110 includes portions of element 100 which define recess 120 and
recess 130. As mentioned above, recess 120 and recess 130 may have
been defined by a mold used to create optical element 100 or formed
after creation of optical element 100.
Returning to process 10, conductive material is deposited on the
surface of the optical element at S14. The material is deposited
such that a portion of the deposited material is disposed within
the defined recess. The conductive material may be composed of any
combination of one or more materials. In some embodiments, the
conductive material comprises nickel. Moreover, the conductive
material may be deposited using any suitable process that is or
becomes known, including but not limited to sputtering, chemical
vapor deposition, sol gel techniques and thermal spraying (e.g.,
twin wire arcing, plasma spraying).
FIG. 4 is a perspective view of optical element 100 after S14
according to some embodiments. FIG. 5 is a cross-sectional view of
optical element 100 as shown in FIG. 4. Conductive material 140 is
depicted covering surface 110 of element 100.
Conductive material 140 is disposed within the recesses defined by
surface 110. A thickness of material 140 within recesses 120 and
130 is greater than a thickness of material 140 on other portions
of surface 110, but embodiments are not limited thereto. Moreover,
a thickness of material 140 on the other portions of surface 110
need not be as uniform as shown in FIG. 5. Generally, a height of
conductive material 140 on various portions of surface 110 may
depend on the technique used to deposit material 140 at S14.
The surface of the optical element is substantially planarized at
S16. The planarization exposes the portion of the conductive
material disposed within the recess. Chemical-mechanical polishing
may be employed at S16 to substantially planarize the surface, but
embodiments are not limited thereto. Planarization may comprise
removing an uppermost portion of the surface of the optical element
as well as an upper layer of the conductive material.
FIGS. 6 and 7 depict element 100 after some embodiments of S16. As
shown, conductive material 140 is disposed within recess 120 and
recess 130 and is substantially flush with adjacent portions of
surface 110. According to some embodiments, conductive material 140
may be electrically coupled to an electrical device and/or to other
conductive traces.
FIG. 8 is a flow diagram of process 200 according to some
embodiments. Process 200 may be performed by any combination of
machine, hardware, software and manual means.
Process 200 begins at S210, at which an optical element is created.
As described with respect to S12, the optical element includes a
surface defining a recess, and may be composed of any suitable
material or combination of materials. The optical element may be
created using any combination of devices and systems that is or
becomes known.
FIG. 9A is a perspective view of optical element 300 created at
S210 according to some embodiments, and FIG. 9B is a
cross-sectional view of element 300. Optical element 300 may be
molded from low-iron glass at S210 using known methods.
Alternatively, separate pieces may be glued or otherwise coupled
together to form element 300. Optical element 300 may comprise an
element of a solar concentrator according to some embodiments.
Element 300 includes convex surface 310, pedestal 320 defining
recesses 322, 324, 326 and 328, and concave surface 330. Recesses
322, 324, 326 and 328 may have been defined by a mold used to
create optical element 300 or formed after creation of optical
element 300. The purposes of each portion of element 300 during
operation according to some embodiments will become evident from
the description below.
A reflective material is deposited on the optical element at S220.
The reflective material may be intended to create one or more
mirrored surfaces. Any suitable reflective material may be used,
taking into account factors such as but not limited to the
wavelengths of light to be reflected, bonding of the reflective
material to the optical element, and cost. The reflective material
may be deposited by sputtering or liquid deposition.
FIGS. 10A and 10B show perspective and cross-sectional views,
respectively, of optical element 300 after some embodiments of
S220. Reflective material 340 is deposited on convex surface 310
and concave surface 330. Reflective material 340 may comprise
sputtered silver or aluminum. The vertical and horizontal surfaces
of pedestal 320 may be masked at S220 such that reflective material
340 is not deposited thereon, or otherwise treated to remove any
reflective material 340 that is deposited thereon.
Next, at S230, an electrical insulator is deposited on the optical
element. The insulator may comprise any suitable insulator or
insulators. Non-exhaustive examples include polymers, dielectrics,
polyester, epoxy and polyurethane. The insulator may be deposited
using any process that is or becomes known. In some embodiments,
the insulator is powder-coated onto the optical element.
Some embodiments of S230 are depicted in FIGS. 11A and 11B.
Insulator 350 is deposited on convex surface 310 or, more
particularly, on reflective material 340. Again, S230 is executed
such that insulator 350 is not deposited on the vertical and
horizontal surfaces of pedestal 320. According to the illustrated
embodiment, insulator 340 is not deposited on concave surface 330
(i.e., on reflective material 340 deposited on concave surface
330).
Returning to process 200, a pattern of conductive material is
deposited on the surface and the electrical isolator at S240 such
that a portion of the deposited conductive material is disposed
within the defined recess. The conductive material may be composed
of any combination of one or more materials (e.g., nickel, copper).
Sputtering, chemical vapor deposition, thermal spraying,
lithography, and or other techniques may be used at S240 to deposit
the conductive material on the surface and on the electrical
isolator.
FIG. 12A is a perspective view and FIG. 12B is a cross-sectional
view of optical element 300 after S240 according to some
embodiments. Conductive material 360 covers pedestal 320 and
portions of insulator 350. FIG. 12B shows conductive material 360
disposed within recesses 322 and 326. Conductive material 360
disposed in recesses 322 and 326 is contiguous with, and therefore
electrically connected to, conductive material 360 disposed on
insulator 350. Although conductive material 360 appears to extend
to a uniform height above element 300, this height need not be
uniform.
Conductive material 370, which may be different from or identical
to material 360, also covers portions of insulator 350. Conductive
material 360 and conductive material 370 define a gap to facilitate
electrical isolation from one another. Embodiments such as that
depicted in FIGS. 12A and 12B may include placing a stencil in the
shape of the illustrated gap on electrical isolator 350 and
depositing conductive material 360 and 370 where shown and on the
stencil. Removal of the stencil may then result in the apparatus of
FIGS. 12A and 12B.
Conductive materials 360 and 370 may create a conductive path for
electrical current generated by a photovoltaic (solar) cell coupled
to element 300. Conductive material 360 and conductive material 370
may also, as described in U.S. Patent Application Publication No.
2006/0231133, electrically link solar cells of adjacent solar
concentrators in a solar concentrator array.
At S250, the surface of the optical element is substantially
planarized to expose the portion of the conductive material
disposed within the recess. Planarization may comprise
chemical-mechanical polishing or any other suitable system. As
described above, planarization may also comprise removing an
uppermost portion of the surface of the optical element as well as
an upper layer of the conductive material.
FIGS. 13A and 13B show optical element 300 after some embodiments
of S250. Conductive material 360 remains disposed within recesses
322 through 328 and electrically coupled to conductive material 360
deposited on electrical isolator 350. Conductive material 360
disposed within recesses 322 through 328 is also substantially
flush with adjacent portions of pedestal 320.
According to some embodiments, S240 and S250 may comprise placing a
material (e.g., wax, polymer) on areas of surface 320 other than
recesses 322, 324, 326 and 328. The material may comprise a
material which resists adhesion to the conductive material. The
material may be dip-coated, contact-printed, stamped, rolled,
painted, etc. onto surface 320.
Conductive material 360 may be thereafter deposited onto the
material and recesses 322, 324, 326 and 328. The material is then
removed using a chemical stripping method, for example, thereby
removing any conductive material that has adhered to the
material.
After formation of apparatus 300 of FIGS. 13A and 13B, a solder
mask defining an aperture is deposited over the exposed portion of
the conductive material at S260. The solder mask may protect the
surface surrounding the conductive material during subsequent
soldering of electrical contacts to the exposed conductive
portions. The solder mask may be deposited using a stencil and a
ceramic spray and/or may be deposited using photolithographic
techniques.
FIGS. 14A and 14B show a perspective view and a cross-sectional
view, respectively, of optical element 300 including solder mask
380. Solder mask 380 defines aperture 385 through which portions of
conductive material 360 are visible. Solder mask 380 may therefore
allow soldering of electrical elements to the visible portions
while protecting other portions of conductive material 360.
In this regard, a terminal of a solar cell is coupled to the
exposed portion of the conductive material at S270. The terminal
may be coupled such that a portion of the solar cell is disposed
over the aperture. The portion of the solar cell may comprise an
area for receiving photons from which the solar cell generates
electrical current.
FIG. 15 is a close-up cross-sectional view of element 300 after
S270 according to some embodiments. Solar cell 390 may comprise a
solar cell (e.g., a III-V cell, II-VI cell, etc.) for receiving
photons from optical element 300 and generating electrical charge
carriers in response thereto. Solar cell 390 may comprise any
number of active, dielectric and metallization layers, and may be
fabricated using any suitable methods that are or become known.
Solder bumps 392 and 394 are coupled to conductive material 360
disposed in recesses 322 and 326, respectively. Solder bumps 392
and 394 are also respectively coupled to terminals 393 and 395 of
solar cell 390. Various flip-chip bonding techniques may be
employed in some embodiments to electrically and physically couple
terminals 393 and 395 to the conductive material disposed in
recesses 322 and 326. In some embodiments, unshown terminals of
solar cell 390 are coupled to conductive material 360 disposed in
recesses 324 and 328 of element 300.
According to some embodiments, a protection layer is applied to the
exposed portions of conductive material 360 disposed in recesses
322 through 328 prior to S270. The protection layer may comprise a
lower layer of nickel and an upper layer of gold. A portion of the
gold layer may dissipate during coupling of the terminal at
S270.
Some embodiments may avoid deposition of solder mask 380 at S260 by
replacing solder bumps 392 and 394 by other interconnects that do
not require melting to couple terminals 393 and 395 to conductive
material 360 disposed in recesses 322 and 326. Examples of such
materials include gold stud bumps and conductive die attaches
including silver-filled epoxy. In these embodiments, the coupling
may be established by known methods such as ultrasonic welding and
other direct chip attachment methods.
According to some embodiments, a thin layer of conductive material
is deposited on entire surfaces 310 and 320 of optical element 300.
Photoresist is then applied to entire surfaces 310 and 320. The
photoresist is patterned and developed such that the photoresist
covers all portions of the conductive material except for exposed
portions where metal traces are desired. Metal plating is applied
which adheres to the exposed portions but not to the photoresist.
The photoresist is then removed, and the thin layer of conductive
material is removed. The thin layer may be removed by selectively
etching in a case that the thin material differs from the metal
plating material. In some embodiments, etch time may be controlled
to remove the thin layer while leaving a suitable thickness of the
metal traces.
Apparatus 300 may generally operate in accordance with the
description of aforementioned U.S. Patent Application Publication
No. 2006/0231133. With reference to FIG. 15, solar rays enter
surface 398 and are reflected by reflective material 340 disposed
on convex surface 310. The rays are reflected toward reflective
material 340 on concave surface 330, and are thereafter reflected
toward aperture 385. The reflected rays pass through aperture 385
and are received by window 396 of solar cell 390. Those skilled in
the art of optics will recognize that combinations of one or more
other surface shapes may be utilized to concentrate solar rays onto
a solar cell.
Solar cell 390 receives a substantial portion of the photon energy
received at surface 398 and generates electrical current in
response to the received photon energy. The electrical current may
be passed to external circuitry (and/or to similar
serially-connected apparatuses) through conductive material 360 and
conductive material 370. In this regard, solar cell 390 may also
comprise a terminal electrically coupled to conductive material
370. Such a terminal would exhibit a polarity opposite to the
polarity of terminals 393 and 395.
The several embodiments described herein are solely for the purpose
of illustration. Embodiments may include any currently or
hereafter-known versions of the elements described herein.
Therefore, persons in the art will recognize from this description
that other embodiments may be practiced with various modifications
and alterations.
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